Disc brakes existed for several decades on motorcycles before making their way to bicycles, if rim brakes were so deficient I think this would have happened much sooner.

That might have had something to do with how laughably awful some early bicycle disc brakes were.

I got my first discs in 1992. They were regarded as the best available at the time. They were more or less OK-- about what I have come to expect from good broken-in drum brakes with appropriate levers. But they were much more expensive than that. And much noisier.

That first pic is amazing. Blast from the past! I didn’t own a bike with discs until about five years ago. They certainly have changed for the better.

One of the worst bicycle disc brake designs has to be that terrifying Phil wood thing from the late 70s(?) It had a rotor made out of an asbestos composite, that was attached to the hub with splines. Not the best plan Phil! They were “prone to shatter”

The problem with rim brakes is not braking power, it is that they need a perfect rim. Off road, rims are likely to be less than perfect before the end of a fast ride, either because of untrued wheel, hit or mud. A rotor is much safer from damage and dirt, thus more reliable. Add to this simple fact, that hydro pistons do require much lighter hand pressure on the levers, making for much more comfortable use of brakes in extreme situations, high speed, down a hill, etc...

It is true that many riders have disc brakes and don’t really need them, but it is also true that many riders wouldn’t be safe without them. We ride fast, heavy, various conditions in all seasons, and that is a good enough reason to want the best brakes.

From my own experience, snow is another disadvantage to rim brakes.
Found out last winter during trail riding (and not on the streets!) that between pulling brake lever and actual braking there can be up to 1 second delay.
It creates thin layer of ice to the rim (after each braking), which first has to be rubbed off in order to brakes start working.
Imagine that riding on streets, between cars.

I'll say again that for any given amount of braking power you need, you can get it more cheaply with rim brakes than with discs. Rim brakes are cheaper, rim brake wheels are cheaper. Rim brake wheels are stronger, so they can be made equally strong with less expensive components.

From my own experience, snow is another disadvantage to rim brakes.
Found out last winter during trail riding (and not on the streets!) that between pulling brake lever and actual braking there can be up to 1 second delay.
It creates thin layer of ice to the rim (after each braking), which first has to be rubbed off in order to brakes start working.

Imagine that riding on streets, between cars.

Mud, wet leaves, and in some cases plain water can be similarly problematic for rim brakes.

On the other hand, even very tiny amounts of oil greatly reduce the effectiveness of disc brakes. Since many disc brakes are actuated by pressurized oil, and they always run in close proximity to mechanisms that must be oiled or greased, this is a common problem. One of my disc brakes is attached to a Rohloff hub that chronically weeps a small amount of oil, and that brake has been more trouble than any rim brake I ever had.

Coaster brakes and drum brakes are the ones to use if you want to avoid your braking being affected by contamination.

Off road, rims are likely to be less than perfect before the end of a fast ride, either because of untrued wheel, hit or mud. A rotor is much safer from damage and dirt, thus more reliable.

You make a better case here for drum brakes than for discs. Disc brake rotors are exposed and can be bent or fouled by the same things that foul your rims.

Greg Herbold, John Tomac, and the other competitors in the then-new sport of MTB downhill racing at the turn of the '90s seemed to do fine with rim brakes. Disc brakes were available to them if they wanted. Shimano's came out in 1975.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

I'll say again that for any given amount of braking power you need, you can get it more cheaply with rim brakes than with discs. Rim brakes are cheaper, rim brake wheels are cheaper. Rim brake wheels are stronger, so they can be made equally strong with less expensive components.

....

Coaster brakes and drum brakes are the ones to use if you want to avoid your braking being affected by contamination.

... Disc brake rotors are exposed and can be bent or fouled by the same things that foul your rims.

Greg Herbold, John Tomac, and the other competitors in the then-new sport of MTB downhill racing at the turn of the '90s seemed to do fine with rim brakes. Disc brakes were available to them if they wanted. Shimano's came out in 1975.

Some really bizarre assertions in here. The thread is about cost and people’s perception of value. Disc brakes are certainly not cost prohibitive. With all due respect to your experience and huge contributions to this forum, it’s like you’re stuck in a 1995 time warp. Your arguments are exactly what I heard when disc brakes first started becoming available to the mass public, but were still considered a techie novelty by most. You realize that the technology has improved a bit in a quarter century, right? Tomac and Overend chose cantilevers over discs (in 1990-something!) even though discs were available to them, and that is somehow an argument in favor of rim brakes today? Want to guess what those guys are riding right now on their personal bikes?

And you’re seriously saying that when it comes to harsh conditions, riders who encounter mud and snow regularly should outfit their bikes with drum brakes?

I think you made a conclusion twenty-five years ago, and now you are unwilling to
consider that your conclusion might be wrong. It happens to the best of us.

"But I will say this-- the strongest rim brakes are stronger than the strongest disc brakes."

But then you go on to say it's about cost. It would cost a normal human being without access to a fabrication shop the price of a whole set of XT discs (or more) to have a custom made brace and brakes like Chalo shows in his post, which *might* outperform *some* discs in *certain* conditions, like say a lab bench heat dissipation test.

But let's go back to the real world. I'll put it to you that an out of the box Acera hydraulic disc brake (low end) will stop better than an XT v-brake (high end) given the same amount of lever effort from the rider, given the same bike which is disc and rim compatible. The cost difference is trivial to none if your bike can take discs.

"But I will say this-- the strongest rim brakes are stronger than the strongest disc brakes."

But then you go on to say it's about cost. It would cost a normal human being without access to a fabrication shop the price of a whole set of XT discs (or more) to have a custom made brace and brakes like Chalo shows in his post, which *might* outperform *some* discs in *certain* conditions, like say a lab bench heat dissipation test.

But let's go back to the real world. I'll put it to you that an out of the box Acera hydraulic disc brake (low end) will stop better than an XT v-brake (high end) given the same amount of lever effort from the rider, given the same bike which is disc and rim compatible. The cost difference is trivial to none if your bike can take discs.

Greg Herbold, John Tomac, and the other competitors in the then-new sport of MTB downhill racing at the turn of the '90s seemed to do fine with rim brakes. Disc brakes were available to them if they wanted. Shimano's came out in 1975.

And now every single competitor uses discs.

Every. Single. One.

If the the strongest rim brakes really were stronger than the strongest disc brakes, then lots of DH competitors would be using them - because they would win more races. They don't.

You seem to be taking this very personally for some reason. No one is saying that rim brakes suck, or that they don't work. They do. But there are some things that disc brakes are better at - and that's why they have taken over the market.

From a personal perspective, I once blew a tire from overheating during a long descent in Luxembourg. (rear tire fortunately.) By the time I got stopped the rim was almost, but not quite, too hot to touch. The combination of that and a high pressure touring tire managed to pop the bead off the rim and expose the tube.

About ten years ago I was on my MTB doing a long, steep descent in a canyon in San Diego. These were with 160mm discs, which weren't the best choice for such descents. When I got to the bottom I got off my bike for a second and my calf accidentally touched the rear rotor. I instantly got a burn, and for about two weeks had the vent-hole pattern tattooed on my calf.

So the disc was that hot but the tire was fine - because the disc is a long, long way from the tire, and there's very little thermal path between the two. Plus which, of course, the disc was dissipating heat a lot faster, since heat flow depends on the difference between the object and the air. You are better off with a disc that is 50C hotter than ambient vs a rim that is 25C hotter than ambient, at least in terms of heat transfer.

Does this anecdote mean that rim brakes suck and you should never use them? Of course not. I used them for twenty years because they were pretty much all that was available - first cantis, then V-brakes. They work. I've used them for heavy ebikes, and they worked ok. But when I can I replace at least the front with a disc because they just work better for me over a wider range of conditions (wet, dirt, not perfectly true rims.) And there are the minor advantages as well - not as much shimmy when stopping with a less than perfect rim, one less thing to mess with when changing wheels/tires, easy upgrade to larger/better versions.

There just isn’t a big enough “face—>palm” emoji for some of these comments.

He has a point, though. With my rim brakes, I can keep pulling the lever harder and they keep braking harder. But when discs get hot enough to fade, that doesn't happen. Pull as hard as you like, but they don't give you any more braking. I've had that happen with Shimano roller brakes, too.

My first modern disc brake (Hayes HMX-1) burned its pads down to their backings in less than 20 miles of city riding. Aftermarket metallic pads from EBC fixed that issue, but I have to say-- I've never had a weird problem like than with a rim brake.

I don't think that most people are heavy enough, or have bikes with long enough wheelbases, to assess which brakes are strongest. Maximum braking with any really good brake would toss them off their bikes. So they have to go by lever response, which in the case of many disc brakes is very strong to the point of being indelicate. That's not the same as stopping power. It's just getting more braking than you intended when you squeeze the lever a little.

It's like power brakes in a car-- they don't make the brakes stronger, they just apply harder with less effort. That's not the same and it's not always a good thing.

As far as being behind the times, remember: I'm a mechanic in a bike shop. I have assessed, serviced and test ridden thousands of bikes in the last few years. I have more contact with bicycle brakes, new and old, than anybody else here who doesn't work in the same field. I don't have the luxury of adopting a silly pet notion like "discs are always better" which could be a reflection of what's on just my bikes. If discs were categorically better, I would know that from experience. What they are-- usually but not always-- is grabbier with a light lever effort. What they are not, is stronger in absolute terms.

There just isn’t a big enough “face—>palm” emoji for some of these comments.

He has a point, though. With my rim brakes, I can keep pulling the lever harder and they keep braking harder. But when discs get hot enough to fade, that doesn't happen. Pull as hard as you like, but they don't give you any more braking. I've had that happen with Shimano roller brakes, too.

My first modern disc brake (Hayes HMX-1) burned its pads down to their backings in less than 20 miles of city riding. Aftermarket metallic pads from EBC fixed that issue, but I have to say-- I've never had a weird problem like than with a rim brake.

I don't think that most people are heavy enough, or have bikes with long enough wheelbases, to assess which brakes are strongest. Maximum braking with any really good brake would toss them off their bikes. So they have to go by lever response, which in the case of many disc brakes is very strong to the point of being indelicate. That's not the same as stopping power. It's just getting more braking than you intended when you squeeze the lever a little.

It's like power brakes in a car-- they don't make the brakes stronger, they just apply harder with less effort. That's not the same and it's not always a good thing.

It would cost a normal human being without access to a fabrication shop the price of a whole set of XT discs (or more) to have a custom made brace and brakes like Chalo shows in his post, which *might* outperform *some* discs in *certain* conditions, like say a lab bench heat dissipation test.

But if you take a set of $20 Tektro or Shimano linear pull brakes, add a $12 set of salmon Kool Stop pads and a $3 Chinese booster arch from eBay, you'll have more gross braking power than just about any disc brake you can name. Not as good as the ones I made after work almost 20 years ago, but more than you can use and still stay on the bike.

That is one way to keep your bike cost reasonable without sacrificing performance.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

Why don't we agree to disagree since nobody has produced quantitative data? Quoting which length of skirt the manufacturers are selling this year or what professional downhill racers use isn't necessarily a reflection of what's best for most individuals.

Hey, you're the one repeating the same assertion based on the fact that you believe it to be true, and for no other reason.

I'm the one with a sample size of thousands and thousands of bikes whose brakes I have tuned personally.

Well, I hate to burst the bubble of authority, but I’ve also tuned thousands of bikes. I was lead mechanic at a high volume pro shop, I was a bike messenger for more than a decade, and I’ve raced as an amateur road, ‘cross, and xc competitor since the early 90s.

Please don’t get me wrong; if we were in a bar or a coffee shop in real life, this would be a spirited and good natured discussion, where I could let you know how grateful I am for your generous input on everything related to ebikes! I have gotten a ton of great info from your posts and I have lots of admiration and respect for your willingness to share what you know.

But this is not a “which oil is best” thread, where there is room for differences of opinion. This is a safety topic that people will rely on to make informed choices about their brake set-up. And we owe it to future readers to give reliable information.

Rim brakes can be made to work perfectly well and can stop your bike, you don’t HAVE TO upgrade to discs in order to be safe. But a good set of disc brakes will work significantly better than rim brakes, and they’re a better value if safety and performance is a priority.

Why don't we agree to disagree since nobody has produced quantitative data? Quoting which length of skirt the manufacturers are selling this year or what professional downhill racers use isn't necessarily a reflection of what's best for most individuals.

Why don't we agree to disagree since nobody has produced quantitative data? Quoting which length of skirt the manufacturers are selling this year or what professional downhill racers use isn't necessarily a reflection of what's best for most individuals.

Before anybody jumps on this saying it's out of date, it does mention the Magura Gustav M disc brake which to my knowledge still hasn't been exceeded among bicycle discs.

There is some hogwash in the above article, but it's not relevant to the brake tests.

Dude. 2003???

I will admit that I’ve tried to find some “objective evidence” for what I know to be true from my own experience, plus every single person I know who rides mtb. Turns out, the ONLY group of cyclists who even debates this issue, besides the quixotic hold-outs in endless sphere, is roadies. That’s right, the Lycra clad, pedal-clippin’, Starbucks sippin’ crowd are the only ones still claiming that rim brakes can be “just as good.” But even those guys (and yeah they’re my friends too) have to admit that discs do work better when it’s wet, when you really need sensitive brake control, etc.

I don't think today's bicycle discs would hold up to the "Mount Washington test" described in the article better than any of the 2003 brakes did. Physics haven't changed, the brakes are about the same size and mass, and their materials are also the same.

E-bikers have a comparable situation to tandemists, in that they work at energy levels that differentiate between brakes with abundant capacity and those with merely adequate capacity. When I weighed over 400 pounds and rode daily in steep Seattle, I was another one of those outliers who could find the differences.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

I don't think today's bicycle discs would hold up to the "Mount Washington test" described in the article better than any of the 2003 brakes did. Physics haven't changed, the brakes are about the same size and mass, and their materials are also the same.

E-bikers have a comparable situation to tandemists, in that they work at energy levels that differentiate between brakes with abundant capacity and those with merely adequate capacity. When I weighed over 400 pounds and rode daily in steep Seattle, I was another one of those outliers who could find the differences.

Hmmm. I mentioned way back in one of my earlier posts that 20 years ago, “big players in the tandem industry made the same arguments against disc brakes that you’re making.” I’ve actually read the article above many years ago, it was an interesting test. I currently ride a Santana Noventa with rim brakes, in Seattle. Great bike, I will never sell it.

But does it strike you as odd that today, in 2018, Santana’s best tandems come with.... *drumroll*.... disc brakes?

But does it strike you as odd that today, in 2018, Santana’s best tandems come with.... *drumroll*.... disc brakes?

Just hype?

It doesn't surprise me either that so many economy cars these days come with cast alloy wheels, when they don't yield any advantages for those cars or drivers. Once folks are made to believe something's better, they'll pay extra for it... even if it's not. Disc brakes and hydraulics play crassly to people's moto-fetishism.

I know I could set up a rim braked bike to pass that Mount Washington test.

This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.